Novel diacyl peroxides

ABSTRACT

3-Alkoxy acyl peroxides having the formula:   IN WHICH R is alkyl containing from 1 to 14 carbon atoms, and X is hydrogen or methyl are new compounds which resemble common diacyl peroxides in manner of decomposition, but exhibit important differences in chemical and physical properties. The new peroxides are liquids at ambient temperatures and possess a higher degree of thermal stability than the commonly used aliphatic acyl peroxides of similar structure and molecular weight. The new compounds, and especially the 3-alkoxyisobutyryl peroxides, are suitable for use as initiators for the polymerization or copolymerization of ethylenic monomers and for the crosslinking of unsaturated polyesters.

llnited States Patent [1 1 Deardorff et a1.

[11] 3,855,315 [451 Dec. 17, 1974 1 NOVEL DIACYL PEROXIDES [22] Filed: Nov. 2, 1972 [21] Appl. No.: 303,039

Related US. Application Data [62] Division of Ser, No. 729,451, May 15, 1968, Pat. No.

[52] US. Cl 260/610 D [51 Int. Cl. l. C07c 73/02 [58] Field of Search 260/610 D [56] References Cited UNlTED STATES PATENTS 2,865,904 12/1958 Seed et a1. 260/949 FOREIGN PATENTS OR APPLICATIONS 679,516 4/1965 Belgium 260/610 Primary Examiner-Bernard Helfin Assistant ExaminerW. B. Lone Attorney, Agent, or FirmHugo E. Weisberger [57] ABSTRACT 3-Alkoxy acyl peroxides having the. formula:

in which R is alkyl containing from 1 to 14 carbon atoms, and X is hydrogen or methyl are new compounds which resemble common diacyl peroxides in manner of decomposition, but exhibit important differences in chemical and physical properties. The new peroxides are liquids at ambient temperatures and possess a higher degree of thermal stability than the commonly used aliphatic acyl peroxides of similar structure and molecular weight. The new compounds, and especially the 3-alkoxyisobutyryl peroxides, are suitable for use as initiators for the polymerization or copolymerization of ethylenic monomers and for the crosslinking of unsaturated polyesters.

5 Claims, No Drawings 1. r NOVEL DIACYL ERoxiDEs CROSS-REFERENCE TO RELATEDAPPLlCATlON This application is a continuation-in-part of applica- 3 tion Ser. No. 662,578, filed Aug. .23, 1967 now abandoned. I

This application is a division of application Serial No. 729,451, filed May 15, l 968 now US. patent 3,728,402, issued April 17, 1973.

BACKGROUND OF THE INVENTION solids at ordinary temperaturesand are supplied. com- The foregoing general formula includes within its structure two distinct classes of 3'-alkoxy diacyl peroxides, namely (-1) 3-alkoxypropionyl' peroxides, and (2) 3-alkoxyisobutyryl peroxides. While these two classes of diacyl peroxides according tothe present invention possess certain similarities in structure and fundamental physical properties,- they differ markedly in other respects, such as, for example, their thermal decomposition rates, and in their performance as polymerization initiators, the isobutyryl peroxides. being distinctly superior in this regard. Accordingly, the propionyl peroxides and the isobutyryl peroxides comprise classes each mercially in granular or powder form.The diacyl peroxides are generally thermaly unstable, and as such are hazardous materials, requiring special precautions in handling and storage.

One of the most widely used peroxides is lauroyl peroxide, which is considered one of the less hazardous diacyl peroxides since it is insensitive to shock and heating it in bulk does not result in deflagration. Ben-,

zoyl peroxide, on the other hand, is both shocksensitive and subject to deflagration inbulk decomposi-' tion.

The known liquid organic peroxides are generally unstable and tend to decompose upon standing at room temperatures, sometimes with explosive violence,'and this property has greatly restricted their use. Efforts have been made to stabilize liquid organic peroxides by the use of additives, such as iodine, and a procedure of this kind is described'in US. Pat. No. 2,415,971.

However, the presence of such additives may exert unfavorable effectsupon the polymerization process when the peroxide is employed as a catalyst or initiator.

Accordingly, there has existed a need for a liquid organic peroxide compound which would be suitable as a catalyst and initiator forpolymerizations, and which would possess a free radical generation rate similar to that of the conventional catalysts, while exhibiting good thermal stability at ambient temperatures.

- SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a novel class of diacyl peroxides having the general formula:

in which R is alkyl containing from 1 to 14 carbon atoms and X is H or CH3. The alkyl group may be of either straight chain or branched structure, but the compounds within contemplation of the invention are those in which' both R substituents are the same, i.e. symmetrical dialkoxydiacyl peroxides. Preferably the alkyl groups contain from 4 to 10 carbon atoms.

Examples of suitable alkyl substituents include butyl, isobutyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, decyl, dodecyl, tridecyl, and tetradecyl.

having their own special characteristics, and are therefore not tobe regarded as equivalents.

' The novel diacyl peroxides of the invention are liquids which are more stable at room temperature than known peroxides of equivalent free radical generation characteristics. They are characterized structurally by' the presence of an ether oxygen in the B-position to theacyl carbon atom. The presence of the ether linkage is.

fundamental to the chemical and physical properties of the peroxides. Thus, for example, the compound 3-(2-ethylhexoxy)-propionyl peroxide of the invention has a molecular weight of 402, which is very close to that of lauroyl peroxide, which is 398, but it is liquid of I low viscosity and very low freezing point, which does not solidify at 65C. All the 3-alkoxy diacyl peroxides of the present invention aremobile liquids at normal temperatures, and even the lower molecular weight derivatives solidify only at very low temperatures. Thus, for example, 3-butoxy-propionylperoxide, which has a molecular weight of 290, solidifies below -l0C., and the compound B- (isobutoxy)-isobutyryl peroxide solidifies at 40"c.

For a given compound to be useful as an initiator for polymerization reactions, there is a relatively narrow and characteristic range of temperature within which the compound must exhibit useful activity. Thus, al-

though a very wide range of thermally-unstable compounds are known and .available as initiators for radical-induced reactions, only relatively few of these compounds are suitable for any particular reaction since these reactions have certain prerequisites in regard to temperature and solubility. Moreover, in some instances, reactions are limited to a particular temperature range because of the limited availability of initiators-with suitable activity.

One such temperature range in which reaction flexibility is limited owing to a lack of suitable initiators is the range from about 25 to about C., and more particularly from about 40 to 55C. This range is of greatimportance in the plastics industry, since a large pro-. I

portion of ethylenic polymerization is desirably or necessarily performed within it. Thus, for example, a major proportion of polyvinyl chloride is produced in the I range 50 to 55C. Heretofore, most of this has been produced with the aid of lauroyl peroxide, an initiator with very low reactivity at these temperatures. As a result of this low reactivity, large amounts of lauroyl peroxide are needed to retain reasonable reaction times.

long reactor cycles, and uneven and undesirable reaction exotherm profiles. Even with these drawbacks, lauroyl peroxide has remained the most commonly used initiator, partly owing to its relatively low hazard potential, and partly because of the limited availability of practical and versatile compounds with equal or better reactivity over the desired temperature range. A comparatively recently developed group of initiators is that of the dialkyl peroxydicarbonates, particularly isopropyl peroxydicarbonate. The latter compound exhibits much greater activity in the temperature range of 40 to 55C. than does lauroyl peroxide, but in addition to poor solubility characteristics in many systems, it possesses hazardous decomposition characteristics unless maintained at very low temperatures and/or in dilute hydrocarbon solutions. Also at the lower'limit of temperature of about 40C., this compound shows rapidly diminished activity. For practical purposes, the polymerization profiles of the peroxydicarbonates resemble fairly closely those of lauroyl peroxide.

Among the most desirable properties of an initiator are: (a) increased reactivity at critical and useful temperature ranges so that substantial conversion of monomer occurs in the early stages of the polymerization,

resulting in a more evenly distributed exotherm throughout the reaction; (b) virtually complete decomposition of the initiator during the reaction cycle; and (c) good solubility in organic solvents.

The foregoing requirements are entirely satisfied by the novel 3-alkoxy-isobutyryl peroxides of the present invention. These compounds are effective as initiators in ethylenic polymerization reactions in the range of 40 to 55C. to an extent which is both surprising and unexpected. Thus, for example, the compound 3-(2-ethylhexoxy)-isobutyry1 peroxide, which is illustrative of the class of alkoxy-isobutyryl peroxides of the present invention, is especially effective as an initiator at the critical temperature of 51C. which is important in vinyl chloride polymerization. Lauroyl peroxide initiates vinyl chloride polymerization very slowly and exhibits an accelerating effect as the reaction proceeds. For instance, in a typical lauroyl peroxide initiated system at 123F. (51C.), about 73% of the polymer is made in the first 88% of the reaction cycle. The remaining 27% of the polyvinyl chloride is formed in the last 12% of the reaction cycle. In contrast thereto, the initiator 3-(2-ethylhexoxy)-isobutyryl peroxide is capable of producing about 60% of the polymer in the first 37% of the polymerization cycle, and the remaining 40% in the last 63% of the reaction period.

The most desirable way to polymerize vinyl chloride is to have the reaction take place at a uniform rate over a fairly short cycle time. Using lauroyl peroxide, the total cycle is 16 hours, with a considerable proportion of the polymerization squeezed into the last few hours. The 3-(2-ethylhexoxy)- isobutyryl peroxide initiator accomplishes the reaction in only 1 1 hours, and with a much more desirable distribution of the polymerization -toward the earlier portions of the cycle.

Although there is a similarity in structure between the propionyl peroxides and the isobutyryl peroxides of the present invention, there is nevertheless a very great difference in their behavior and effectiveness as initiators for polymerization, as well as in terms of relative kinetic stability.

Decomposition rate studies of the thermal stability of the 3-alkoxypropionyl peroxides of the invention in comparison with such known peroxides as lauroyl peroxide and benzoyl peroxide indicate that the compounds of the invention are intermediate in rate of thermal decomposition between lauroyl and benzoyl peroxide. Moreover, the length or structure of the alkoxy group has little or no influence'on the rate of decomposition. The alkoxy-propionyl peroxides exhibit half-lives longer than, but fairly comparable to lauroyl peroxide. Hence their behavior as initiators is also fairly comparable.

The half-lives exhibited by the 3-(alkoxy)-isobutyryl peroxides are, however, very different from those of either the alkoxypropionyl peroxide or lauroyl peroxide, being far shorter. The half-life of an initiator, expressed in hours, and typicallydetermined on a 0.2 molar solution of a given compound in benzene, at a given temperature, such as 60C., is an excellent indicator of the effectiveness of compound as an initiator for ethylenic polymerization, such as vinyl chloride polymerization.

As mentioned previously, the 3-alkoxy-isobutyryl peroxides of the present invention are superior initiators of ethylenic polymerization. Thus, the half-life of the 3-alkoxyisobutyryl peroxide compound 3-(2-ethylhexoxy)-isobutyryl peroxide is about 0.3 hour at 60C., whereas the half-life of the corresponding 3-alkoxy-propionyl peroxide, namely 3-(2-ethylhexoxy)-propionyl peroxide at the same temperature is about 42 hours. The ratio of half-lives of the propionyl to the isobutyryl peroxide is 42/03 indicating that the isobutyryl peroxide is about times faster in its decomposition rate, and also indicating that the isobutyryl peroxides as a group will initiate many times faster than the propionyl peroxides.

Studies on polymerization of vinyl chloride have indicated that the 3-alkoxy-isobutyryl peroxides of the present invention not only produce much faster polymerization rates than the corresponding 3-alkoxypropionyl peroxides, but very much faster than lauroyl peroxide, as a matter of fact, whereas it is not possible to produce polyvinyl chloride resins of very high molecular weights with lauroyl peroxide or the 3-alkoxy propionyl peroxides because of their relative inactivities at the low temperatures required, it is quite readily possible to produce such results using the 3-alkoxy isobutyryl peroxides.

Thus, as is shown below, polymerizations carried out in the 25- 40C. temperature range are impractical to carry out with the former initiators, whereas the 3- alkoxy isobutyryl peroxides will give high degrees of 4' conversion within commercially feasible times.

As is demonstrated in the examples below, it is possible to obtain polyvinyl chloride polymers having specific viscosities of 0.8 and even as high as 1.0, whereas the conventional initiators do not produce polymers in excess of ca. 0.55 under practicable production conditions.

These great differences between the 3-alkoxyisobutyryl peroxides as a class, on the one hand, and the 3-alkoxy-propionyl peroxides or lauroyl peroxide, in respect to kinetic activity levels, are believed to be due to a combination of the oz-branched chain structure and the presence of a B-oxygen atom in the alkanoyl groups. Chain length also plays a part, but only to 3 limited extent.

In conventional diacyl peroxides, an active oxygen content in excess of 5.0% is generally regarded as resulting in a shocksensitive, hazardous material. However, in the case of the 3-alkoxyisobutyryl peroxides and the 3-alkoxy-propionyl peroxides of the present invention, no indication of shock sensitivity or tendency toward deflagration is exhibited even in the butoxy dereaction hibit a lack of sensitivity to heating in bulk, while offer-- ingthcconvenience of beingliquids. This, together with their ability to maintain free radical generation rates similar to or greatly in excess of the commonly 6 and 10 ml. portions were placed in 18 m X 125 mm test tubes. The tubes were purged .with nitrogen, stoppered and placed in a constant temperature bath. Samples were removed at minute intervals and analyzed for 5 residual active oxygen content by a standard iodometric method. The results are summarized in the following table:

Table 2 3-Alkoxypropionyl and -3-'Alkoxyisobuty1'yl Peroxides Decompmition Rate Studies Te mture Rate (mutant Haiti it Peroxide K Hr Hours Z-ethylhexoxy propionyl 60 0.0162 42 70 0.0794 8.75 80 0.265 33.22 iso-hexox ro ionl 60 0.01765 yp p y I 70 0.0872 7.9 80 0.285 2.4 n-butoxy propionyl 60 0.0174 39.8

- 70 0.0796 8.7 80 0.262 2.64 we -22 8-5216 et exox )iso u y y tyry 30 0.041 16.9

0.180 3.85 3-( isobutoxy)isobutyryl 25 0.027 25.6

. 40 0.201 3.5 lauroyl 60 0.0453 15.3 70 0.17 4.0 80 l.0 benzoyl 60 0.0145 47.8 70 0.036 I).

Disappearance of active oxygen (iodometric) 0.1 N solutions in benzene.

used diacyl peroxides, provides a high degree of useful ness both as catalysts or initiatorsfor polymerization and cross-linking reactions.

Typical examples of the 3-alkoxy-isobutyryl peroxides of the invention include:

3'-(2-ethylhexoxy)-isobutyryl peroxide 2-(isobutoxy)-isobutyryl peroxide Typical examples of 3-alkoxy-propionyl peroxides of the invention include;

3-(2-ethylhexoxy)-propionyl peroxide 3-(isohexoxy)-propionyl peroxide 3-(n-butoxy)-propiony1 peroxide 3-(isobutoxy)-propionyl peroxide The physical properties of six of these compounds, in comparison withthose of lauroyl and benzoyl peroxides are set forth in the following table. The active oxygen content of the peroxides was determined by liberation of iodine and titration with standard thiosulfate solution:

Table l Properties of 3-Alkoxy-propion l And 3-Alkoxy-isobutyryl Peroxi es The novel 3-alkoxy-isobutyryl and 3-alkoxypropionyl peroxides of the invention may be prepared by well known methods of synthesis applicable to the 35 preparation of aliphatic diacyl peroxides. Such methalkoxypropionyl chloride with dilute hydrogen perox-' ide in the presenceof an alkali metal hydroxide such as. sodium, potassium or lithium hydroxide. The hydrogen peroxide may, for example, have a concentration ranging from about 10 to about 70% by weight and the ratio of hydrogen peroxide may, for example, range between Active .Oxygen Freezin D Viscosity Peroxide Theory Found Pt.C. cs.25C.

(2-ethylhexoxy)propionyl 3.98 3.51 0.954 16.9 (isohexoxy)propionyl 4.63 3.52 65 0.957 19.5 (n-butoxy)propionyl 5.52 5.18 l2 giso-butox )propionyl 5.52 5.25 13 0.993 9.28 2-ethy1 exoxyhsobutyryl 3.78 3.12 -40 0.920 16.4 3-(lsobutoxy)isobutyryl 5.03 4.45 -40 0.958

peroxide 1 lauroyl 4.02 3.83 +48 solid benzoyl 6.61 6.5 +106 solid Commercial samples used as standards of comparison.

Kinetic studies of thermal decomposition ot the above siz peroxides of the invention, in comparison withlauroyl and benzoyl peroxides, were conducted in dilute benzene solution..Solutions of approximately 0.1

N peroxide is reagent grade benzene were prepared about 0.5 and 1.0 moles per mole of acyl chloride.

The alkali metal hydroxide may be supplied to the reaction, for example, in the form of an aqueous solution having a concentration between about 10 and 50% by weight. The ratio of alkali metal hydroxide may vary range of about to C., preferably about 2 to 6C. Total reaction time will usually lie between about 0.5 and 3 hours.

The 3-alkoxy-isobutyryl chloride or the 3-alkoxypropionyl chlorides may be prepared, for example, from the corresponding 3-alkoxy-isobutyric acid or 3-alkoxypropionic acid by acylation with phosphorus trichloride in accordance with known methods.

In accordance with a further aspect of the invention, it has been found that the 3-alkoxy-isobutyryl peroxides can be used conjointly with a second initiator so as to achieve a uniform rate of the polymerization reaction over a fairly short cycle time. Thus, for example, a dialkyl peroxydicarbonate may be used in combination with a 3-alkoxy-isobutyryl peroxide to produce a polymerization rate which is neither slower in the beginning, nor which accelerates greatly toward the end of the conversion. This enables an essentially rapid polymerization reaction, such as that of vinyl chloride, to be maintained at a level which can be controlled by the conventional cooling equipment used, and which remains at essentially the same level throughout the polymerization. In the case of vinyl chloride polymerization, which is advantageously carried out at a temperature between about 125 and 135F., a suitable initiator mixture, in accordance with the present invention, is from. about 2 to 6 parts by weight of 3-alkoxyisobutyryl peroxide per 1 part of dialkyl peroxydicarbonate, preferably about 4:]. When using 3-(2-ethylhexoxy)-isobutyryl peroxide, a suitable peroxydicarbonate for admixture therewith is di('sec.- butyl)-peroxydicarbonate, the ratio of the isobutyryl compound to the peroxydicarbonate being about 4 to 1 parts by weight. This mixture provides a short reaction time and almost uniform conversion in the polymerization of vinyl chloride, there being a variation of only about 5F. in the jacket temperature from beginning to the end of the reaction and consequently, a very constant difference between the internal temperature and the jacket temperature of the reactor. It will be understood that varying the ratio of peroxide to dialkyl peroxydicarbonate will permit changes in the conversion rate and the exotherm profile of the reaction. In the dialkyl peroxydicarbonate, the alkyl group may contain 1 to 6 carbon atoms, such as for example, methyl, ethyl, propyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, butyl cyclohexyl, 2-ethyl hexyl, lauryl, etc.

The 3-alkoxy-isobutyryl peroxides of the invention, and the 3-alkoxypropionyl peroxides as well, provide effective catalysts and initiators in the polymerization or copolymerization of ethylenic monomers, and especially for the preparation of such polymers of vinyl halides or vinylidene halides. These include vinyl chloride polymers, and copolymers of vinyl halides such as vinyl chloride, with at least one other polymerizable monomer, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinylidene chloride, methyl methacrylate, methyl acrylate, propylene, vinyl cetyl ether and the like. The peroxides may also be used as catalysts in the polymerization of olefins, such as ethylene, propylene and butylene, or in the copolymerization of such olefins with other mono-olefins, such as halogenated ethylenes,

vinyl ethers, vinyl chloride, vinyl acetate, vinyl propionate, styrene, and acrylates and methacrylates. They may also be used as initiators in the cross-linking of unsaturated polyesters, such as those made from propylene glycol, maleic anhydride, phthalic anhydride, and styrene.

In such polymerizations, the amounts of peroxides employed will depend upon the reactants, but may lie in the range of about 0.01 to 0.5% and upward.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples serve to illustrate the practice of the invention, but are not to be regarded as limiting:

EXAMPLE 1 Preparation of 3-(Isohexoxy)-Propionyl Peroxide Temperature was maintained at 2 to 6C. during the addition, which required 50 minutes, and for an additional 60 minutes. The oil product was separated and washed three times with 300 ml. portions of water to give 39 g. of a colorless oil with 3.53% active-oxygen.

EXAMPLE 2 Preparation of 3-(2-Ethylhe xoxy)-Propionyl Peroxide This compound was prepared by adding 66 g. of 3-( 2- ethylhexoxy) propionyl chloride to a stirred and cooled solution containing 62.5 g. of 25% sodium hydroxide, 14.6 g. of 50% hydrogen peroxide and 262 g. addition of water. The reaction kettle was maintained at -3C. to 15C. during the time of addition which required [.5 hours. Stirring was continued for 45 minutes during which time the temperature was allowed to rise to 15C. The product, separated as an oil, was removed and washed two times with 400 ml. portions of distilled water to give 37 g. ofa slightly viscous and colorless oil with 3.49% active oxygen (Theory 3.98% active oxygen).

EXAMPLE 3' Polymerization of Vinyl Chloride The effectiveness of the peroxide of Example 2 as an initiator-in comparison with lauroyl peroxide and benzoyl peroxide, in the polymerization of vinyl chloride was tested by preparing three formulations having the The polymerization was carried out at a temperature of 142F. for a period of 18 hours.

The properties of the resulting polyvinyl chloride are summarized in the following table:

' TABLE 3 v Lauroyl 3-( 2-Ethylhexoxy) Benzoyl lnltlator Peroxide Propionyl Peroxide Peroxide Yield of Polymer, Parts 92.5 93.2 93.6 lSpecific Viscosit 0.318 0.321 0.325

eat Stability, inutes at 350F.

To first yellow 30 30 15 To black 60 70 60 l v a I In comparison with lauroyl peroxide, the peroxide of EXAMPLE 6 Example 2 resulted in increased and greater heat stability, while in cmparison with benzoyl peroxide, it showed less tendency toward early decomposition.

EXAMPLE 4 3-(2-Ethylhexoxy) lsobutyryl Peroxide This compound was prepared by adding 105 g. of 3- (Z-ethylhexoxy) isobutyryl chloride to a stirred and cooled solution containing 90 g. of 25% sodium hydroxide, 20.5 g. of 50% hydrogen peroxide and 35.0 g. of water. The reaction kettle was maintained at 3 to 5C. during the time of addition which required 30 minutes. Stirring was continued for an additional 2 hours during which time the temperature was allowed to rise to C. The oil product was separated and washed three times with 100 ml. portions of distilled water to get 86 g. of oil containing 3.02% active oxygen by iodometric determination. The physical constants were:

. The peroxide of Example 4 was compared with 3-(2- ethylhexoxy) propionyl peroxide in the polymerization of vinyl chloride in formulations of the following composition:

Pans by Weight I Vinyl Chloride I00 Initiator 0. l Methylcellulose 0.6 Water 200 The polymerization was carried out at a low temperature of 86F. for a period of 18 hours. Properties of the resulting polyvinyl chloride are summarized in the following table:

Table 4 Compound of 3-(2-Ethylhexoxy) Initiator Example 4 Propionyl Peroxide Yield of polymer,- parts 86.7 nil Heat Stability, Minutes at 350F. 1 To black I95 This indicates the total inactivity of the propionyl compound of this invention.

Polymerization of Vinyl Chloride In a separate experiment the 3-(-2-ethylhexoxy)- isobutyryl peroxide of Example 4 was compared with lauroyl peroxide in formulations of the following composition:

Parts by weight Vinyl Chloride l 00 Initiator 0. I Methylcellulose 0.6 Water 200 The polymerization was carried out at a temperature of 104F. for a period of 18 hours. Yields and properties of resulting polyvinyl chloride are as follows:

Iauroyl Initiator Example 4 Peroxide Yield of polymer, parts 89.7 25 S cific viscosity 1 sp eat stabilit minutes at 350F. To blacl; 250 I I EXAMPLE 7 Preparation of 3 -(isobutoxy )'isobutyryl peroxide The compound was prepared by addition of 380 g. of

3-(isobutoxy) isobutyryl chloride to a stirred and cooled solution containing 384 g. of 25%,sodium hydroxide, 82 g. of 50% hydrogen peroxide and 800 g. of water. Temperature was maintained at 0C. during the addition, which required l5 minutes and for 15 minutes beyond. At that time the oil product was separated and washed three times with I00 ml. portions of distilled water to give 255 g. of oil product containing 4.45% active oxygen .by iodometric determination. The oil product had a refractive index of 25C.-of 1.4292 and specific gravity 25/l5.6 of 0.96.

EXAMPLE 8 The peroxide of Example 7 was evaluated in the polymerization of vinyl chloride in the following formulation:

Parts by Weight Vinyl chloride Initiator 0. l Methylcellulose 0.6 Water 200 Table 3-lsobutox lnltiator Propionyl eroxide Example 4 Example 7 Yield of Polymer, parts nil 88.3 88.9

EXAMPLE 9 Cross Linkingof Unsaturated Polyester. Resins A mixture was prepared of the following ingredients in the molar ratios shown:

Maleic anhydride 1.0 mole Phthalic anhydride 1.0 mole Propylene glycol 2.2 moles To 7 parts by weight of the foregoing mixture, which had an acid value of 45 50, there were added 3 parts of monomeric styrene. Immediately prior to curing there was added 0.1% of 3-(2-ethylhexoxy) propionyl peroxide and the mixture was cured by heating to form a cross linked polyester resin. Peroxides of the invention were compared with commercial diacyl peroxides (designated the kick off temperature) and at the peak in the table below and is an effective measure of the monomer conversion rate at any instant. The more nearly AT is constant from the beginning to the end of the polymerization, the more nearly is the conversion rate constant throughout the process. Differences in initial and final AT and in maximum and minimum AT are shown as absolute numbers, without regard to sign:

Table 7 Initiator: 0.05/0.0 l 25 CBP/BPD AT final AT initial 32 AT max. ATmin. 34

It is evident that in the polymerization as performed exotherm, in 'this example the initiator combination provides the Table 6 Kick Off Time Peak Exotherm Peroxide Minutes Temp. C. Time, Min. Temp.C.

Example 2 9.0 95 10.9 175 Example 4 2.3 72 4.0 135 Lauroyl Peroxide 4.25 91 6.3 176 Benzoyl Peroxide 5.3 96 7.0 170 EXAMPLE 10 shortest reaction time and the most uniform conversion Polymerization of Vinyl C hloride With a Mixture of 3-(2-ethylhexoxy)-isobutyryl Peroxide and Di(sec.- butyl)-Peroxydicarbonate A jacketed pressure reactor capable of being heated or cooled by automatically controlled water flow was charged with 100 parts by weight of vinyl chloride monomer, 200 parts deionized water, 0.1 parts Methocel (methyl cellulose), and a mixture of 0.05 parts of 3 -(2-ethylhexoxy)-isobutyryl peroxide and 0.0125 parts of di(sec.'-butyl)-peroxydicarbonate. The internal temperature of the reactor was set to be controlled at 124F. The difference between the jacket temperature and the internal reactor temperature is designated AT rate. In fact, over the first 72.5% of the reaction time there is an absolute AT change of only 5, which makes for an easily and efficiently controlled polymerization with the most efficient overall use of polymerization.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5,855,515 Dated December 17, 1974 Inventor(s) Donald L. Deardorff et 8.1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Heading, following the Inventors, there should be set forth:

-- Assignee: Teknor Apex Compan Signed and sealed this 1st day of April 1975.

(SEAL) Attest:

C. MARSHALL DMEN Commissioner of Patents and Trademarks RUTH. C. MASON Attestina; Officer F ORM PO-1050 (10-69) USCOMM-DC 6037 6-P69 LLS. GOVERNMENT PRINTING OFFICE: 

1. A DI 3-(ALKOXY) PROPIONYL PEROXIDE SELECTED FROM THE GROUP CONSISTING OF DI 3-(2-ETHYLHEXOXY) PROPIONYL PEROXIDE, DI 3-(ISOHEXOXY) PROPIONYL PEROXIDE, DI 3-(ISOBUTOXY) PROPIONYL PEROXIDE, AND DI 3-(N-BUTOXY) PROPIONYL PEROXIDE.
 2. Di 3-(2-ethylhexoxy) propionyl peroxide.
 3. Di 3-(isohexoxy) propionyl peroxide.
 4. Di 3-(isobutoxy) propionyl peroxide.
 5. Di 3-(n-butoxy) propionyl peroxide. 